Two dimensional convergent/divergent variable area exhaust nozzles are combinable with a reverser vane system which includes a plurality of movable vanes to optimize engine operation in vertical takeoff and landing (VTOL) and short takeoff and landing (STOL) aircraft. In order to improve the life of the various members incorporated in the particular nozzle assembly, cooling air is usually directed internally to those parts in contact with the hot exhaust gas stream. The cooling air is obtained from the engine compressor section and ducted to the members to be cooled. Consequently, the quantity of cooling air required has an impact on engine efficiency. To opimize engine operation, variable flow or on/off type flow controllers are utilized which reduce or increase cooling airflow in response to nozzle configuration. For example, in U.S. Pat. No. 4,098,076 to Young, et al., a cooling air management system for a two-dimensional exhaust nozzle is disclosed which includes several valves with associated control mechanisms. Of course, the more complex the cooling system, the more weight is added to the nozzle assembly.
With two dimensional convergent/divergent vectoring nozzles, a reverser vane system is usually included which is isolated from the exhaust stream during the forward thrust configuration by an isolation valve. Since the isolation valve is in contact with the exhaust gas stream, cooling is utilized to extend its operational life. During the transition from forward to reverse thrust, the isolation valve unports and allows the exhaust stream to enter a reverser vane access passage, providing access to the reverser vane system. Consequently, during reverse thrust operation, cooling air is more properly directed to the walls of the reverser vane access passage. Since cooling air is required for the reverser vane system, but not for the isolation valve, diverter means may be utilized for directing cooling flow from the isolation valve during forward thrust operation to the reverser vane system during reverse thrust operation. Such diverter means must be capable of maximizing cooling efficiency and optimizing engine operation while minimizing nozzle complexity and weight.